Btw, I had a game where My capital was just 20 tiles away from Vetrar at beginning of the game. I held my breath and played. It wandered away from my lands and into Kraxis' lands and terrorized them. And it looked like it was going to keep on wandering away and away so I sent three armies towards Vetrar and kited him back into his wildlands. Took me about 30 turns but vetrar is back in the snowy wildlands where he stayed put until I got a ashwake dragon pet to bring him down very early in the game.
To kite, leave a weakling army just two tiles away from vetrar so that he will want to nom nom on the army of mcnuggets but keep it two tiles away, if Vetrar change his mind and go after something else, chase him until he chases you again then flee again and vice versa.
Rinse and repeat until vetrar is back in the wildlands where you can kill him to guarantee a wildland clear. Oh and don't get your army trapped by rivers, frozen rivers is uncrossable I noticed it just in time lol.